Spark-plug



A. L. RIGGS.

SPARK PLUG.

I APPLICATION FILED JUNE 27, 1.919. 1 355 421 Patented Oct. 12, 1920.

WITNESSES ALFRED Lamar. meesor rrrrsnuaen, Pmmvmi srABx-rLnG.

To all whom. it may concern:

Be it known that I, ALrRnp LEANDER Rreos, a resident of Pittsburgh, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Spark-Plugs, of which the thereto; (Figi .therethroug than structed.

following is a specificatio I This invention relates to spark plugs of the type in which an auxiliary sparkgap is provided at the upper end-of the plug and which is visible so that it can be seen whether current is being supplied to the electrodes or is being shortcircuited forany reason..- The present invention is an improvement of my Patent No. 1,265,518, granted May 7, 1918, and reissued October 15,1918,No. 14,538..

The primary object of the present invention is'to provide a; spark plug of the above named type in which the auxiliary spark at-. tachment issimpl er and cheaper to manufacture and. to apply to the insulating core in such plugs as heretofore con- --Inthe accompanying drawings Figure 1 is aside elevation of. the upper portion of a plug showing the improvement applied Fig. 3 is a vertical sectional view taken on the line 33, Fig. 1; Fig. 4 is a horizontal section taken on the line 44, Fig. 1; and Fig. 5 is a similar view showing a modification. .o

' In the drawings 10 represents the upper portion of the porcelain Or other insulating core of the plug. This is provided with a flat top end faceand with a central axial bore and near the upper end with, an external annular groove 11. Mounted upon the core is a cap or sleeve 12, the lower end .of which is crimped or flanged inwardly, as at l3,'to engage in the groove 11 ofthe core. The upper end -of this cap or sleeve is likewise crimped or flanged inwardly, as at 14, and slightly below its upper end said cap or sleeve is conbdviled on both si es,' as sown at 17,- in

tracted, orming an internal shoulder 15. A disk of glass or other transparentmaterial 16 has its ed set in the groove formed by the. inturne flange 14 and internal shoulder 15. Inorder that saidglass may be tightly wedged in said groove and pre- -is preferably orderTHatitimay wedge into the groove. To facilitate formation of the bottom flange Specification of Letters Patent.

l l Application filed June 27,

2 is a central vertical section Patented Oct. 12, 1920. 1919. Serial No. 301,240. i r

13 and top flange 14 the metal of the edges of the sleeve is preferably provided with a senes of V-shaped slits or notches extending into the materlal only a short distance and which permit the portions of the edges of the metal between said slits or notches to be readlly flanged or bent inwardly.

'Withinthe sleeve 12 in firm electricalcontact therewith and resting upon the top face of the core is a terminal ring 18, provided with an inwardly projected sparking point 19, which cooperates with the upper end of metal rod 20 extending down through the axial bore in-the core and which rod forms one terminal of the main ,spark gap. The space between the upper end of this rod and the projection 1'9, of the ring 18 forms the auxiliary spark gap which is visible through the glass 16 in order that the character of the spark: can be observed.

' is. ring 18 may be either a solid ring, as

shown .in Fig. 4 or may be a wire bent to ring formas shown at 18, one end turned inwardly to terminal 19.

The sleeve or cap 12 is split along one slde, shown at 21, and is clamped to the core, and at the same time clamps the glass 16 and ring 18, by means of a pair of ra dially extending ears 22 and 23, one formed on each edge of said sleeve, by bending a tongue of the metal radially. These ears Fig. 5 having form the spark are perforated to receive a clamping bolt or screw 24 which enters a threaded hole 'in a block 25 from which projectsthe bindingpost 26 to which-the, ignition wire is secured.

The block 25 serves as a nut. This block is made square or of other polygonal form and to keep it from turning when tightening the clamp screw 24 the lower edge of the ear 23 is bent outwardly, as at 27 and bears against the lower face of said nut. Preferably the cap or sleeve is provided with a seiles of ventilating openings28.

The cap or sleeve 12 can be very cheaply manufactured by blanking it out from sheet metal having projecting ears 22 and 23 at opposite sides thereof, and then bending said blank to tubular form and crim in inwardly the portions 13, 14 and 15. ai ea or sleeve is secured to the core by means 0 a the screw 24 and .nut 25, and this acta'lso serves to clamp tight-ly'i'n position"- the glass 16 and terminal ring 18 This construction required a minimum number of parts thus decreasingmaterial and upon an insulating core, said sleeve being slit longitudinally and provided on each edge at the slit with a perforated radial ear, a binding-post provided with a threaded opening, and a clamping screw extending through the perforated ears and engaging the threaded opening of the bindingpost and securely clamping said cap to the core and securing said binding post to said sleeve. a

2. In a spark-plug, a sleeve arranged to be mounted upon an insulatingcore, said sleeve being "slit vertically and provided at each edge at said slit with a radial perforated ear, one of said ears having its lower edge turned horizontally, a bindingpost having a non-circular portion engaging the out-turned portion of said ear and provided with a threaded opening, and a clamping screw passing through the perforated ears'and engaging the threaded opening of the binding-post.

3. In a spark plug, the combination with an insulating core provided with an axial bore and with an external annular groove near its upper end, a rod extending through said axial bore, a sleeve having an in-turned lower edge engaging with the annular groove in the core, an inturned upper edge, an inwardly projecting shoulder slightly below its upper ed e and being split verticall and provide on. each edge with a per orated radial ear, a terminal ring in said sleeve and cooperating with'the upper end of said rod, a transparent pane havin its periphery held between the in-turne upper edge of the sleeve and the internal shoulder adjacent thereto, and a clamping screw and nut cooperating with the perforated ears for clamping said sleeve to the core and clamping the terminal ring and transparent pane in said sleeve.'

4. In a spark plug, in combination, an inan in-turned lower end engaging in the annular groove in, the core, said sleeve being split vertically and provided at each edge atsaid slit with a radial perforated ear, :1

terminal ring in said sleeve in contact there with and cooperating with the upperend of said rod, a transparent pane in the up er end of said sleeve, a-binding-post prov1 ed with a threaded opening, and a clamping "screw extending through the perforated ears and engaging the threaded opening of the bindin -post and serving to clamp the sleeve on t e core and clamp the terminal ring and transparent pane in said sleeve.

5. In a spark plug, in combination, an insulating core provided with an external annular groove near its upper end, a sleeve having an in-tur'ned lower end engaging in saidgroove,said sleeve being split vertically and provided at each edge at said 'slit with V a radial perforated ear, a binding post pro vided with a threaded opening, and a clamping-screw extending through the perforated ears of the sleeve and engaging the threaded opening of the binding post and serving to clam the sleeve on the core and secure the bin ing post thereto.

In testimony whereof my hand. I

ALFRED LEANDEB; RIGGS. Witness: I i I I have hereunto set 

